Electric regulating system



March 1, 1932.

w. THOMPSON 1,847,910 ELECTRIC REGULATING SYSTEM Filed Oct. 8, 1923 Inventor:

Patented Mar. 1, 1932 UNITED STATES PATENT OFFICE LOUIS W. THOMPSON, OF BCHENECTADY, NEW YORK, ASSIGNOB TO GENERAL mic COMPANY, A CORPORATION 01' NEW YORK ELECTRIC REGULATING "STE! Application flied 0mm 0, ms. was Io. 1,001.

My invention relates to electromagnetic devices and electric regulating systems and particularly to such systems which comprise a control magnet having a solenoid connected so as to be energized in accordance with the condition to be regulated, and a core adapted to be actuated by said solenoid to control the regulating means.

An object of my invention is to provide an improved construction of control ma net whereby the desired pull characteristic 0 the magnet may be obtained over an extended range of movement of the core of themagnet and whereby the desired regulation may be secured throughout theentire range of movement.

Another object of my invention is to provide an improved construction of the control ling magnet whereby the setting of the magnet may be readily varied.

My invention will be better understood from the following description taken in connection with the accompanying drawings, and its scope will be pointed out in the appended claims. 7

In the accompanying drawings, Fig. 1 shows one embodiment of my invention Fig. 2 shows a modification of the embodiment shown in Fig. 1, and Fig. 3 shows another embodiment of one feature of my invention.

Referring to F ig. 1, 1 represents an alternating current circuit which'is supplied from a source 2 and which, it will be assumed, supplies a load, not shown, requiring a constant voltage to be impressed thereon in order to function properly. For controlling the voltage of the circuit 1, sections of a resistor 3 are arranged to be connected in series with circuit 1 by means of a magnet 4, which actuates a curved arm 5 so that it rolls over the contacts 6 which are connected .to different points of the resistor. Any suitable means such as a cup 7 containing mercury and a movable contact 8 connected to the movable arm 5 may be provided for maintaining an electrical connection to the curved arm 5 as it moves over the contacts 6. \Vhile I have shown the preferred arrangement for main taining an electrical connection to the arm the middle contact, about which the arm ro-- of maximum pull in its normal operatin position. The core 10.is directly connecte to the arm 5 b means of a stem 11 secured to the core an a light stiff flat member 12 one end of which is pivotally secured to the stem 11 and the other end of which isles tened to the contact arm 5. By means of the construction shown, the contact arm 5 can be readily removed from the contacts 6 so that they can be cleaned. The solenoid 9 is wound on a non-magneticspool and so mountzfiidlais to have an unconfined external magnetic It will be observed that as the contact arm 5 moves over the contacts 6 the weight of the contact arm varies the force required to be exerted on the core to move the arm. When the arm 5 is in the position shown, the center gravity of the arm is substantially above tates at this time, and therefore the solenoid has to exert a force only sufficient to move the core in order to move the contact arm 5. When, however, the contact arm 5 is in engagement with the contacts to the right of the middle contact, the center of gravity of the arm is to the left of the point about which the arm is rotating so that the weight of the contact arm 5 tends to lift the core 10. When the arm 5 is in engagement with the contacts to the left of the middle contact, the center of gravity of the arm is to the right of the point about which the arm is rotating so that the weight 'of'the contact arm tends to push the core 10 down. Therefore, in order for the regulator to maintain a constant voltage across the circuit 1, means must be provided to compensate for the variations in the force required to move the core due to the weight of the arm 5 as it moves over the contacts so that a given current through the solenoid can maintain the core at any point in its range of movement.

Furthermore it is evident that it is desirable that the core should have as great a movement as possible for a given change in current through the solenoid when the voltage changes so that very sensitive regulation may be obtained.

1 or accomplishing these desired results a magnetic member 13, preferably of soft iron, is placed below the lower end of the core 10 and another magnetic member 14, preferably of soft iron, is placed above the upper end of the core. These magnetic members ma held in place by any suitable means suc as the brackets 15 and 16, respectively, which are fastened to the support 18 of the solenoid 9. Preferably, the bracket 16 is made of magnetic material and the bracket 15 is made of non-magnetic material. The stem 11 extends through an openin in the magnetic member 14: so that the mem r acts as a guide for the stem. Also a rod 17, which is secured to the bracket 15 and which extends up into a hole in the bottom of the core, steady the core.

The magnetic members 13 and 14 o erate in the followin r manner to produce t e desired results. is the voltage across the circuit 1 tends to decrease, the core 10 dro s down so that the contact arm 5 successive y engages the contacts 6 to the right of the middle contact thereby decreasing the number of sections of resistance in series with the circuit 1. Since the weight of the arm 5 tends to lift the core under these conditions it does not take so much current through the solenoid to exert the necessary pull on the core to maintain it in a given position as it would if only the solenoid were lifting the core. Therefore the regulator tends to undercompound. As the core 10 drops, however, the air gap between the magnetic member 13 and the core decreases so that the reluctance of the path of the leakage flux through these parts is decreased. Consequently there is a stronger pull between the core and the magnetic member 13 which tends to move the core down farther and thereby increase its travel for a given change in current in the solenoid. The magnetic member 13 is so arranged that this increase in pull compensates for the up ward force produced by the weight of arm 5 as well as the change in the pull of the solenoid due to the change in the position of the solenoid so that with normal voltage across the circuit 1, the force exerted on the core by the solenoid is just sufficient at any point in the path of movement of the core to maintain the contact arm in engagement with any one of the contacts 6 tothe right of the middle contact.

\Vhen the voltage of the circuit 1 tends to increase, the core 10 moves up and the movable arm 5 rolls over the contacts 6 to the helps to guide and left of the middle contact so that more sections of the resistance 6 are connected in series with the circuit 1, and the weight of the arm 5 tends to push the core 10 down. Under these conditions the magnet 4 tends to over- COIIIPOllIld' as the solenoid has to exert more force to holdthe core in a given sition. As the core 10 rises in the solenoid, owever, the air gap between the top of the core and the magnetic member 14 decreases so that the pull between the core and the member increases and moves the core up farther so that the travel of the core is increased. The magnetic member 14 is so arranged that the increase in pull between the member 14 and the core compensates for the force exerted by weight of the arm 5, as well as the change in the pull of the solenoid due to the change in the position of the core in the solenoid so that with nor mal voltages across the circuit 1, the force exerted on the core by the solenoid is just sufficient at any point in the path of movement of the core to maintain the contact arm in engagement with any one of the contacts to the left of the middle contact.

It will, therefore, be observed that by means of the magnetic members 13 and 14 a given current through said solenoid will maintain the core at any point in its range of movement notwithstanding the varying force exerted thereon by the arm as it rolls over the contacts 6. Consequently the regulator will maintain an almost absolutely constant voltage throughout its range of regulation. Also, the magnetic members effect a greater movement of the core for a given change in voltage than if there were no magnetic members provided.

Furthermore it is evident that if the regulator were arranged so as to operate only over a portion of the contacts shown, such for ex ample as only the contacts to the right or to the left of the middle contact, one of the magnetic members 13 and 14 could be omitted.

In order to change the setting of the magnet 4 so that it will operate to maintain the voltage of the circuit 1 constant at different values I provide an adjustable short circuited winding 19, which is shown as an adiustablc ring, preferably of copper, around he core. This short circuited winding is preferably adapted to be secured to the core in any suitable manner such as a screw 20 which extends through the short circuited ring and engages the core.

It will be observed that when the ring is moved so that it is cut by more of the flux produced in the core by the solenoid, the ring is more strongly repelled by the solenoid and also the reluctance of the magnetic circuit of the magnet is increased so that it takes a higher voltage to maintain the core in a given position. Thcrcf ore the voltage, which the regulator maintains constant, may be readily changed by merely changing the posi modifying the pull on memb tion of the short circuited coil relative to the core.

While it is preferable to secure the ringto the core so as to obtain both the repel ing action and change in the reluctance, it is evident that the ring could be adjustably secured to the bracket 15 as shown in Fig. 2. With such an arrangement, however, the repelling force on the ring has no effect upon the setting of the magnet.

It is evident that the magnetic members may be used on both alternating and direct currentmagnets to accomplish the desired results whereas the adjustable short circuited winding will be efi'ective only on alternating current magnets.

While I have shown the ment of my invention in w ich the two magnetic members perform the double function of compensating for the effect of weight of the arm actuated b the core of the magnet and of increasing the movement of the core for a given change in current through the solenoid, I desire it to be understood that my invention is not limited to the use of the magnetic members for accomplishing this double function as I find that they ma be used merely to increase the movement 02 the core for a given change in the current through the solenoid. This feature of my invention, for example, may be embodied in a contactmaking voltmeter, such as shown in Fig. 3, in which the core actuates a pivoted arm 12 carrying a contact 21 which is adapted to engage the stationary contacts 22 and 23. As is well known in the art, it is desirable that contacts 22 and 23 should be far enough apart so that movable contact 21 can disengage one of the stationary contacts before it enga es the other and at the same time it is desira le that this movement should be effected in response to a very small variation in voltage if close regulation is required. I find that by placing magnetic members above and below the core the desired movement of the core and the desired sensitiveness can be obtained.

While I have shown and described several embodiments of my invention, I do not desire to be limited thereto but seek to cover in the appended claims all those modifications which fall within the true spirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent of the United States, is,-

1. An electromagnet comprising a solenoid having a substantially unconfined external magnetic field, a core extending within said solenoid and arranged to float in normal operation with its entering end within the region of maximum pull, a magnetic member in spaced relation with one end of said core for said core, and nonmagnetic means for supporting said magnetic 2. An electromagnet comprising a solenoid referred embodicore changes so as to com .ations in the force having a substantially unconfined external magnetic field, a core extending within said solenoid and arranged to float in normal operation with its enterin end within the region magnetic members pomovable control element requiring a di erent operating force in different operating operatively connected to positions, a core said control element, asolenoid adapted to actuate said core, and a ma etic member in the magnetic field produced operative to exerted on said core as the nsate'for the varirequired to actuate said control element.

4. An electromagnetic device com rising a movable-arm having a shifting fu crum, a core operatively connected to said arm so that the weight of said arm as its fulcrum shifts changes the amount of force that has to be applied to said core to move noid adapted to acuate said core, and a magnetic member arranged adjacent each end of said core so that one assists the ull of said solenoid on said core and the ot the pull of said solenoid magnetic members being respect to the core that as core changes to move said so positioned with the position of the arm the forces exsaid arm, a soleer opposesv on said core, said by said solenoid I produce a changein the force position of said ertedby said members compensate for the variations in the force produced by the weight of said arm. i

- -5. A magnet comprisin a solenoid, a core extending within-said so enoid and adapted to be maintained by a given energization of said solenoid in a plurality of positions in-' termediate the limits of predetermined range of movement, a movable arm actuated by said core and arranged so that the force required to move said arm varies with the position of the core, and a magnetic member arran adjacent to one end of said as the position of said core changes to compensate for the variations in the force produced by the movement of said arm.

6. A magnet comprising a solenoid, a core extending within said solenoid and adapted to be maintained by a given energization of said solenoid in a plurality of positions intermediate the limits of a predetermined range of movement, a movable arm actuated by said core and arranged so that the force required to move said arm varies with the posit-ion of the core, a magnetic member arranged adjacent to one end of said core, and a core and operative,

second magnetic member arranged adjacent core that as the position of said core changes the forces exerted by said members compensate for the variations in the force produced by the movement of said arm.

7. A magnet comprising a solenoid, a core, a movable arm actuated by said core and arranged .so that the force required to move said arm varies with the position of the core, and a magnetic member arranged in the magnetic field produced by said solenoid, said magnetic member being arranged to change the pull exerted on said core by said solenoid so that a given current through said solenoid maintains said arm at any point in its range of movement.

8. A magnet comprising a solenoid, a core,

a movable arm actuated by said core and arranged so that the force required to move said arm varies with the position of the core, and a magnetic member arranged ad acent each. end of said core so that as the core moves the change in air gaps between the core and the magnetic members varies the reluctance of the magnetic circuit of the magnet in such a manner that a given current through said solenoid is arranged to maintain said arm at any point in its range of movement.

9. In a regulating system, a magnet comprising a solenoid connected to be responsive to the condition to be regulated, a core arranged to be actuated by said solenoid, a

' movable arm actuated by said core and arranged so that the force uired to move said arm varies with the position of the core, and magnetic means operative to produce a change in the pull exerted on said core as the position of said core changes so as to compensate for the variations in the pull re quired to move said arm.

10. In a regulating system, a magnet comprising a solenoid connected to be responsive to the condition to be regulated, a core arranged to be actuated by said solenoid, a movable arm actuated by said core and arranged so that the force required to move said arm varies with the position of the core, and a magnetic member arranged adjacent to one end of said core said magnetic member being arranged to change the pull exerted on said core as the position of said core changes so as to compensate for the variations in the pull required to move said arm.

13. An alternating current magnet comprising a solenoid, a core adapted to be acproduced b the movement of said arm, and

an adjusta le short circuited winding surrounding said core whereby the energization of the magnet r uired to hold the core in an position may varied.

n witness whereof, I have hereunto set my hand thisfith dav of October, 1923.

' LOUIS V. THOMPSON.

11. In alternating current device comprising a solenoid, a core adapted to be attracted by said solenoid, an adjustable short circuited winding surrounding said core whereby the energization of the magnet required to hold the core in any position may be varied.

12, An alternating current device comprising a solenoid, a core adapted to be attracted by said solenoid, a ring of conducting material surrounding said core and means for securing said ring to said core in various positions of adjustment to vary the setting ot the magnet. 5 

